Sift flour, sugar, baking powder, cinnamon, and nutmeg together in a large bowl.

Whisk milk, pumpkin, egg, and oil together in a separate bowl until smooth. Gently stir milk mixture into the flour mixture until just combined; add more milk, 1 tablespoon at a time, if the batter is too thick. Batter should be thick but pourable and slightly lumpy.

Heat a lightly oiled griddle over medium-high heat to 350 degrees F (175 degrees C). Drop batter by large spoonfuls onto the griddle and cook until bubbles form and the edges are dry, 1 to 3 minutes. Flip and cook until browned on the other side, about 1 minute more. Repeat with remaining batter.

Serve pancakes warm with butter and maple syrup.